The present invention generally relates to ski poles and in particular to ski poles having composite titanium shafts.
Conventional ski poles are generally comprised of a hollow tapered shaft made up of aluminum or other light weight metal. A hand grip is mounted to one end of the shaft, typically a non-tapered end, while a basket and tip are mounted to the other or tapered end of the shaft. The tip is constructed from an impact resistant material, such as metal. This prevents the shaft from incurring damage when struck against a hard surface, such as a rock, during skiing. The basket is mounted to shaft generally adjacent to the tip and is configured to prevent the ski pole from descending into the snow during use.
A significant limitation of the aluminum ski pole is that it is easily damaged during normal skiing activities. Being relatively soft, aluminum ski poles are notorious for becoming permanently deformed and breaking as a result of the bending loads encountered during skiing. Another limitation of aluminum ski poles is that they have a low resistance to abrasion and are easily cut or scratched. The cuts are often the result of the ski pole shaft abrasively contacting various surfaces, such as icy snow conditions, during use. While being light in weight, the limitations of aluminum ski poles with respect to durability and deformation resistance has made it desirable for designers to try and advance in ski pole technology.
In recent years, alternatives to the conventional aluminum shafted ski pole have captured the favor of a large portion of the skiing population. Numerous producers have introduced ski poles in which the shafts are composites of synthetic resins and filaments. While being more resilient under bending forces than aluminum, these known composite ski poles continue to lack sufficient strength and still experience failure at an unacceptable rate. Additionally, during regular skiing activities, filament-type ski poles represent a significant hazard to the skier's hand or other body portions and can break since they shatter exposing splinters. Even without completely breaking in half, splinters can be exposed near the surface of the pole as a result of bending loads causing the pole to crack and the filaments to separate. While offering some structural advances over aluminum shafted ski poles, the known ski poles having composite shafts still exhibit some safety limitations.
Accordingly, it is an object of this invention to provide a composite ski pole that offers improvements in terms of safety and structure while overcoming the limitations of the prior art. The present invention therefore has as some of its objects, provision of a ski pole which is lightweight, resistant to abrasion, resistant to permanent deformation and does not splinter when cracked or completely broken.
In general appearance, the composite ski pole of this invention is similar to prior ski poles in that it includes a shaft having a hand grip, a tip, and a basket mounted to it. The shaft itself has a composite construction which includes a thin-walled tube made of a titanium alloy. The titanium alloy tube is reinforced with an inner or stiffening tube. As more fully discussed below, this stiffening tube can be made from a variety of alternative materials. In one embodiment, the exterior diameter of the stiffening tube substantially corresponds with the inner diameter of the titanium alloy tube and the stiffening tube is inserted into the titanium alloy tube so that its exterior surface will be in intimate surface-to-surface contact with the inner surface of the titanium alloy tube. While it is believed that a press-fitted engagement between the titanium alloy and stiffening tubes is sufficient to keep the tube secured together, an adhesive or other bonding agent can be used to more positively bond the tubes together.
In an additional embodiment of the invention, a core element, such as foam, is positioned within the inner cavity of the stiffening tube. The core serves to dampen vibration in the shaft, further stiffens the shaft, and also enables increases the shaft's resistance to crushing.
When provided as briefly described above, the titanium alloy tube provides the shaft of the ski pole with its lightweight and high strength characteristics. While being quite rigid, the titanium alloy tube still exhibits a significantly high yield point that enables it to deflect under substantial bending loads without becoming permanently deformed. By employing the stiffening tube in conjunction with the titanium alloy tube, the titanium alloy tube is still permitted to bend, but is substantially prohibited from bending in an amount which would approach its yield point and result in permanent deformation.
According to another aspect of this invention, a method for manufacturing the titanium composite ski pole of the present invention includes the steps of first providing a hollow tube of titanium alloy and then providing a hollow tube of stiffening material. The tube of stiffening material is inserted into the titanium alloy tube with the exterior surface of the stiffening tube being in intimate surface-to-surface contact with the interior surface of the titanium alloy tube. As mentioned above, an adhesive may be applied between the two tubes to positively bond the tubes together. After the stiffening tube and titanium alloy tubes have been mounted together, the tubes are cut to an appropriate length for the ski pole shaft. An impact resistant tip is then mounted to one end of the ski pole shaft while a hand grip is mounted to the opposing end. Adjacent to the tip, the basket is secured to the ski pole shaft.
As seen from the summary presented above, the ski pole of this invention is lightweight, generally rigid and offers high performance characteristics. The composite construction of the shaft of this ski pole prohibits the shaft from being loaded beyond its yield point in all but the most extreme bending conditions. This results in the present invention being highly resistant to permanent deformation and collapse. The titanium exterior of the present invention further offers a high degree of resistance to abrasion and increases the durability of the ski pole. Additionally, the ski pole of the present invention will endure a substantial amount of deflection without any resulting splintering and thereby offers safety advances over prior ski pole construction.
While the above description constitutes the preferred embodiments of the present invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope and fair meaning of the accompanying claims.